MOTOR VEHICLE EMISSIONS

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MOTOR VEHICLE EMISSIONS

• Exhaust (tailpipe) (CO, NOx, VOC, PM)
• Evaporative (VOC)
• Resting
• Diurnal heat build
• Hot soak
• Running
• Refuelling

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MOTOR VEHICLE EMISSIONS

• Regulated (criteria pollutants)
• CO, NOx, NMHC, PM
• Non-regulated
• Individual (speciated) HCs
• carbonyl compounds (alcohols, aldehydes, ketones)
• Air toxics, e.g. benzene, toluene, ethylbenzene,
  1,3,butadiene, formaldehyde, acetaldehyde
• CO2 (i.e. fuel economy)

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EXHAUST EMISSION MEASUREMENT

• Simulated driving conditions
• Mass Emission rates in g/km for light duty
  vehicles (LDV) on a chassis dynamometer
• Mass Emission rates in g/kWh for heavy duty (HD,
  diesel) engines on an engine dynamometer
• Actual driving conditions
• On-board measurement systems
• Tunnel studies
• Remote sensing, g/L of fuel burned

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EVAPORATIVE EMISSION MEASUREMENT

• SHED Test, Sealed Housing Evaporative
  Determination
• Carbon canisters attached to various points on
  vehicle to adsorb HC vapors

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DRIVING OR OPERATING CYCLES

• Actual vs Synthesized
• Transient, steady state, multi-mode
• Modal analysis
• Acceleration
• Cruise
• Deceleration
• Idle

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EXHAUST EMISSION TESTINGBasic principles

• Operate vehicle (or engine) on treadmill,
  simulating real driving conditions
• Collect and dilute all of exhaust with constant
  volume sampling system (CVS)
• Sample and analyze dilute exhaust
• Correct for contribution from dilution air
• Emitted mass volume of dilute exhaust X
  concentration
• Mass emission rate mass/distance or mass/energy

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EXHAUST EMISSION TESTINGOther considerations

• Use a standard fuel (e.g. indolene)
• Ensure that the starting conditions are uniform
  (preconditioning)

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THE FEDERAL TEST PROCEDURE(FTP-75)

• Length 11.09 miles
• Time 1877 600 s
• Average velocity 21.3 mph
• Max. velocity 56.7 mph
• Time spent in different modes
• Idle 17.3
• Cruise 20.5
• Acceleration 33.7
• Deceleration 26.5

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THE FEDERAL TEST PROCEDURE(FTP-75)

• Phase 1, 505 s, 3.6 mi (Bag 1) Cold transient
• Phase 2, 866 s, 3.9 mi (Bag 2) Stabilized
• Soak, 600 s
• Phase 3, 505 s, 3.6 mi (Bag 3) Hot transient
• (Phase 1 Phase 2) referred to as UDDS or LA4

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FTP-75 Weighted mass emission rates
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Supplemental FTP

• US06 Simulates the more aggressive (high speed
  and high acceleration/deceleration) current
  driving styles relative to Los Angeles driving of
  the 1960s
• SC03 attempts to quantify the effect of air
  conditioning load on vehicle emissions

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TUNNEL STUDIES

• Measure air flow through tunnel
• Analyze air going in and out of the tunnel
• Determine average mass emission rate of the
  vehicle fleet passing through the tunnel from a
  mass balance

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Tunnel Study Sample Scheme
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Sampling at the Cassiar Tunnel

• Challenge Collect representative PM samples
  from a tunnel safely, without interfering with
  traffic flow.

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REMOTE SENSING

• Measure relative concentration of CO, HC, NOx,
  CO2 in vehicle exhaust.
• Calculate the emitted mass of pollutants per unit
  quantity of fuel, assuming an empirical formula
  for fuel and doing a carbon balance.

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Fuel based emission factors by remote sensing
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EMISSION FACTORS

• Amount of pollutant emitted per unit activity
• g/km, (distance travelled)
• g/kWh, (mechanical energy delivered)
• g/L, (quantity of fuel burned)
• For a single vehicle with given engine and
  emission control technology, the factors that
  influence the emission factor are speed,
  acceleration/deceleration, trip length, ambient
  temperature
• Vehicles with similar size, engine, and emission
  technology may be expected to show similar
  emission behaviour

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EMISSION FACTORS AND EMISSION MODELLING

• Regulated emissions from new vehicles vs
  emissions from in-use vehicles
• Emissions surveillance program to test emissions
  from thousands of in-use vehicles at different
  ages in the U.S.
• Emission modelling from motor vehicles involves
  the consideration of different types of vehicles
  and their driving conditions to arrive at a grand
  total

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REAL WORLD EMISSIONS

• Small fraction of gross emitters in the vehicle
  fleet account for a large fraction of total
  emissions
• Emissions during short periods of fast
  acceleration (high power, fuel rich operating
  conditions) much higher than constant speed
  operation
• Sampling error associated with emissions
  surveillance program

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ON-BOARD EMISSION MEASUREMENT

• Exhaust concentrations
• Engine parameters
• Mass emission rates

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Environment Canada, ERMDON-BOARD EMISSION
MEASUREMENT EQUIPMENT
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ON-BOARD EMISSION MEASUREMENTH. C. Frey et al,
at North Carolina State U. with CleanAir
Technologies OEM-2100 equipment
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• Galio SMART 2000xfl
• on-board emission measurement system.
• Exhaust emissions measured in (k)g/hr, (k)g/mile,
  (k)g/bhp during real driving cycle.